Single solution photographic developing and fixing bath



Patented Feb. 4, 1941 OFFICE v SINGLE SOLUTION PHOTOGRAPHKC DEVELOPING AND FG Garnet Philip Ham,

. i American Cyanamid Company,

a corporation of Maine BATH Riverside, Coma, assignor to New York, N. Y.,

No Drawing. Application April 4,, 1940, Serial No. 327,782

9 Claims.

This invention relates to photographic baths which are combined developing and fixing solutions for silver halides.

There have been in the past sporadic attempts to produce a solution which would both develop and fix silver halide photographic material. Such a product would solve a very important problem particularly in X-ray photography where a photographic bath is desired that would develop to a predetermined density and then fix so that accu-- rate timing is not necessary. The problem of obtaining uniform reproducible density is also an important one and which could be solved by a combined developing and fixing solution which would operate satisfactorily.

With one exception, the proposals in the past have been unsatisfactory as the nature of the im-, age developed has not been satisfactory and fogging and other diflicultles have been encountered.

A more recent development has obtained practical results. This bath is based on the use of certain reducing sugars in the combined developing-fixing solution. The best products obtained with reducing sugars do show satisfactory images and give reasonably reproducible densities. The products also have satisfactory keeping qualities if not exposed to actinic light for too long a period of time. However, in spite of the fact that useful results may be obtained with combined developing and fixing baths using reducing sugars or other analogous carbohydrates, these baths have been open to the very serious objection that the emulsion speed in the case of photographic negatives is greatly reduced and has to be compensated for by increased exposure or otherwise under-exposed, low-density images are obtained. This is a. very serious handicap for many purposes because high emulsion speed is one of the most important properties of modern negative material.

During investigations which led to the development of the prooess'of the present invention, the effects of varying quantities of fixing ingredients such as sodium thiosulfate was investigated and it was found thata combined developing and fixing bath could be produced merely by reducing the concentration of the thiosuliate to a very low figure of the order of magnitude of about 10%. Such baths operate effectively with clear development and fixing and adequate contrast, but they were exhausted by a single use to a point where satisfactory images could not be produced.

According to the present invention, it has been found that: combined developing and fixing solutions can be prepared by the use of aminobenzoic I such as sodium carbonate.

acids and their salts, particularly anthranilic acid, which show good contrast control and decreased eflect on the emulsion speed. In fact, with some of the preferred baths of the present invention, there is but little or no loss in emulsion 5 speed with many classes of negative material. The baths of the present invention are also characterized by excellent keeping qualities and by a relatively low sensitiveness to actlnic light.

It is a further advantage of baths of the present invention that they do not exhaust so rapidly and therefore can be reused.

The factors of emulsion speed and rate of exhaustlon are to some extent connected. Larger 15 amounts of thiosulfate permit the re-use of the baths on larger amounts of negative material, but at the cost of somewhat increased effect on emulsion speed. The best compromise between maximum emulsion speed and minimum exhaustion of the bath will vary for different uses. Thus, for example, where a bath is going ,to be used only once or twice, the compromise giving maximum emulsion speed will be chosen.

It is an advantage of the present invention that it is generally applicable with various types of silver halide developers. Thus, it can be used in developers which have hydroquinone as their main developing agent or in the more common metol-hydroquinone types. The different solutions will give different results depending on the nature of the developing agents used as is well known in the art, and it is an advantage of the present invention that it is generally applicable to the common types of silver halide developers.

The fixer, which is a thiosulfate, may be ordinary sodium thiosulfate or it may be any of the amino-amidine thiosulfates such as guanidine sulfate or mixtures 01. guanidine and sodium thiosulfates which are described and claimed in the U. -s. patent to Barnes, No. 2,114,494. The developlng and fixing solutions of the present in vention may use various alkalies to bring about developing action; It is an advantage of the present invention that the ordinary alkalies may be used such as sodium hydroxide, sodium carbonate, borax, borate mixtures, and the like. In many cases we have found that improved results are obtained when an amino-amidine carbonate is used either alone or admixed with other alkalies We do not claim here the use of guanldine carbonate per 56, as this has been described and claimed in the U. S. Patent 2,174,494, cited above. Good results may also be obtained by using alkalies containing a quatera has a pH value'of 11.2 at 25 C.

nary ammonium compound such as described in U. 8. Patent 2,179,790.

The invention will be described in greater detail in conjunction with the following specific examples. The parts are by weight except in the case of liquids where they are in corresponding pants by volume.

Example 1 A photographic solution was prepared as follows:

Parts Water at 25 C 100.00 Sodium bisulfite 1.22 Hydroquinone (p-dihydroxybenzene)- 1.22 Potassium. bromide 0.50 Sodium hydroxide 1.30 Anthranilic acid or guanidine anthranilate 0.40 0.50 Sodium thiosulfate 2.50 Ammonium hydroxide 0.50

The solution is made up by dissolving each component in the order as given and results in a clear, light amber colored solution with a pH value of approximately 11.00 at 25 C. and a reduction potential of 0.44 v. at 25 C.-, adaptable for processing films 0i medium photographic speed or medium X-ray film.

The film or plates to be processed are placed in the solution for a minute period at 18 C. and then water washed for minutes. The dried film or plate is comparatively free from stains and chemical fog and the surface is smooth and free from reticulation.

Example 2 A photographic solution was prepared as follows by dissolving the components in the order given.

The solution is light amber in color, clear, and Medium speed photographic film or plates are processed for an 8-10 minute period at 18 C., and a satisfactory negative of density less than that obtained by using the solution in Example 1. is obtained.

Example 3 A photographic solution is made up by dissolving the components in the order given belcizvzrt Water at C 100.00

Metol (monomethyl-p-aminophenol sulmost water-white, clear, and has a pH value 01' 9.6 at 25 C. It is satisfactory for processing mm. panchromatic film at 18 C. for 25 minutes which results in negatives tree from stains.

Example 4 A solution is prepared as in Example 1 using 1.50 parts of guanidine thiosuliate in place 01' the 2.50 parts 0! sodium thiosuli'ate mentioned. The development time was 13 minutes tor a medium-fast photographic emulsion and results were similar to those obtained in Example 1.

. Example 5 A 2.5 parts of ammonium thiosulfate were used instead of the sodium thiosulfate in the formula for the solution of Example 1 and medium-fast photographic film or plates were processed at 18 C. for a period 01' ten minutes. Results were similar to those obtained in Example 1.

In the above examples guanidine anthranilate or anthranllic acid is used in preparing the combined developing and fixing solutions. The presthe solution as a whole is rather strongly alkaline, the anthranilic acid in the solution actually forms an anthranilic. acid salt or anthranilatc. and the same-is true it any 01' the other amino benzoic acids are used.

What I claim is:

1. A single solution silver halide developing and fixing bath comprising a silver halide developing mixture, an aminobenzoate and a silver halide fixing agent. I I 4 2. A single solution silver halide developing and fixing bath comprising a silver halide developing mixture, an amino benzoate and a thlo sulfate. l

3. A single solution silver halide developing and fixing bath comprising a silver halide developing mixture, an anthranilate and a thiosuliate. 4. A single solution silver halide developing and fiidng bath comprising a silver halide developing mixture, an amino and a th-iosuli'ate.

.amidine anthranilate.

5. A single solution silver halide developing and fixing bath comprising a silver halide developing mixture, guanidine anthranilate and a thiosuli'ate.

6. A single. solution hydroquinone developing and fixing bath comprising a developing mixture containing hydroqulnone, an amino benzoate and a thiosulfate.

'7. A single solution hydroquinone developing and fixing bath comprising a developing mixture containing hydroquinone, an anthranilate and a thiosulfate.

8. A single solution metol-hydroquinone developing and fixing bath comprising a developing mixture containing hydroquinone and metol, an amino benzoate and a thiosulfate.

9. A single solution metol-hydroquinone developing and fixing bath comprising 9. developing mixture containing hydroquinone and metol an anthranilate and a thiosuliate.

GARNE 'IPHILIPHAM. 

